I've made a couple of messages folders by mistake and I'm wondering if it's possible for me to delete them, it's kind of hard to navigate that area with the false (mispelled) headings among the real ones.

The plural form of 'octopus' is formed by totalling the number of legs in the overall group, convert that into a numeric Greek prefix and add 'pus'. For example, 3 octopese would be 24 legs, so that's an 'Icosatesserapus'. Two octopese eating a one-legged diver would be a 'Heptadecipus'.